LIVE POLIO IRUS VACCINES

292 Efficacy-Laboratory Evidence
TABLE 6. READMINISTRATION OF CHAT VIRUS THREE TO FIVE MONTHS AFTER BIRTH
FIRST ADMINISTRATION
SECOND ADMINISTRATION
OUTCOME INFANTS REINFECTED POSITIVE ANTIBODY
RESPONSE
Infected,
POSITIVE
Antibody
Response
(No.)
6
2/6 3/6
Infected,
NO Antibody
Response
5
5/5
5/5
NOT Infected,
NO Antibody
Response
2
0/2 0/2
* Response in one infant uncertain.
an antibody response after the first administration
of virus, were readily reinfected in all five
cases (Table 6). Excretion of virus after the
second feeding was detected as long as the stools
were examined (up to two weeks), despite a previous
average excretion after the first feeding of
over four weeks. That is to say, instead of having
been rendered resistant to reinfection these
five infants appeared to be as susceptible to infection
as previously unexposed infants. However,
the infants were not immunologically
tolerant, as shown (Table 6) by the antibody response
that followed reinfection in at least four
of these five infants.
SUMMARY AND CONCLUSION
We found that neonatal premature infants were
highly susceptible to infection with poliovirus,
but that detectable antibody production was
stimulated in only about half the instances of
infection. The presence of passively acquired
antibodies in the circulation of the infants seemed
to have no effect on either intestinal infection or
active antibody response to living attenuated
poliovirus. Intestinal infection with the same
virus was readily reestablished in infants who
had previously been infected but were without
antibodies, in contrast to the resistance to reinfection
of successfully vaccinated premature
infants. However, immunologic tolerance to
poliovirus was not demonstrated, for all the infants
who were infected were shown to be capable
of an immune response to the attenuated poliovirus.
ACKNOWLEDGMENTS
The assistance of Walter Lauterer, M.D., Jane
Sitnek, R.N., and Toby Goldschneider, and the
cooperation of Paul Gyorgi, M.D., in carrying out
this study, is gratefully acknowledged.
REFERENCES
1. Koprowski, H., Norton, T. W., Hummeler, K.,
Stokes, Jr., J., Hunt, A. D., Flack, A., and
Jervis, G. A.: Immunization of infants with
living attenuated poliomyelitis virus. J. Am.
M. Assn. 162: 1281-1288 (Dec. 1) 1956.
2. Martins da Silva, M., McKelvey, J. L., Prem,
K. A., Johnson, E. A., and Cox, H. R.: Immunization
with orally administered attenuated
live-virus poliomyelitis vaccine. Am. M.
Assoc. J. Dis. Child. 96: 624-625 (Nov.) 1958.
3. Plotkin, S. A., Koprowski, H., and Stokes, Jr.,
J.: Clinical trials in infants of orally administered
attenuated poliomyelitis viruses. Pediatrics
23: 1041-1062 (June) 1959.